This invention relates, in general, to hydrocarbon producing wells capable of producing oil and gas and relates, in particular, to a portable, prefabricated production package for operating such a well under controlled conditions once the well has been properly drilled and prepared.
The installation and operation of hydrocarbon producing wells involve a number of well known steps. For purposes of describing the present invention, these preliminary steps will be discussed only briefly to establish the environment in which the present invention is employed.
Conventionally, suitable drilling apparatus is initially employed to drill a bore to the necessary depth to reach the hydrocarbon deposits. An outer metal casing is then installed in the bore to approximately one-half of the elevation above sea level of the depth of the hole to lock off the surface water and water table. It will, therefore, be appreciated that the depth of the casing can vary depending on circumstances and governmental requirements. In any event, once the casing is in place, a casing head or hanger is then secured on its top.
The outer casing is, of course, cemented in conventional fashion from the bottom up. Another, inner casing is next inserted and cemented in with a latch plug being employed to keep the cement from coming up the tube. The inner casing wall is then "fractured", which essentially involves the utilization of chemicals, hydrostatic, or hydraulic pressure to fracture the rock deposit so that a series of fissures or fractures will extend radially outwardly from the bore produced by the drill. Finally, the bottom of the casing is driven out in order to enable the well to receive the hydrocarbons. This is basically accomplished by perforating or shooting holes in the inner casing. This permits the hydrocarbons to flow into the central bore and eventually up through that bore between the inner and outer casings.
All of these steps are conventional and, at this point, the well is essentially ready for production with the next problem being to get the hydrocarbons out of the geological formation in which they are found, through the tubing, to enable them to be utilized or processed further as the case may be.
Depending upon the pressure in the well, there are primarily three different ways of accomplishing this. First, where the pressure is adequate, a free flow will occur and it is merely necessary to hook up the external plumbing. Second, where the pressure is not adequate for free flow, a plunger lift arrangement can be used. Third, if the pressure is not adequate to bring the hydrocarbons up naturally, a jack pump is employed. No detail will be entered into at this point on the structure or operation of these alternatives since these are expedients which are well known to those of ordinary skill in this art.
As noted, the well is now ready for production by one of the just mentioned methods. Typically, in many geological formations, however, the material coming out of the well is essentially a mixture of oil, gas, and salt water with lesser amounts of other chemicals and it is necessary to separate these elements before they can be employed, further processed commercially, or disposed of.
In order to accomplish this, once the well is in the condition just described, i.e., the site has been prepared, the hole has been drilled, the hole has been fractured, and the pumping mechanism is in place, it is then necessary to "plumb" the site.
This plumbing involves the installation of numerous tanks, tubing, lines, meters, valves, etc. The object of the plumbing is to provide means to separate the gas from the oil and then to separate the water from the gas and the oil as well as to store the elements thus separated. Current practice revels that there are a number of difficulties which are encountered in this plumbing operation.
First, the plumbing normally has to be done on the job site which involves advance planning and acquiring, assembling, and transporting all the necessary tools and apparatus to the site. One difficulty is that if anything is overlooked, the installers either resort to field expedients or lose time in returning to their base to complete the inventory. This is obviously costly in terms of labor and time.
Another related difficulty obviously is that these wells are outdoors and exposed to the environment, thereby making it necessary to perform all of the plumbing functions in what is often inclement weather. This often leads to hurried or careless installation.
Additionally, conventional on-site plumbing is costly because of the man hours involved. For a typical well, it usually takes about three actual working days by a three man crew to complete the plumbing. This, of course, assumes no interruptions because of weather.
The difficulty that is often encountered is that the roustabouts or other personnel sent to the well site to perform the plumbing operation are, at best, inexperienced and not necessarily highly skilled. Due to the difficult working conditions and lack of personnel skill, it is quite frequently the case that the well is simply not plumbed correctly. This creates significant safety problems because very significant pressures are involved with a typical well and if incorrect valves, for one example, are employed, serious danger is created for the personnel who have to operate and service the well over its subsequent operational life.
Another difficulty is that these wells will not be plumbed uniformally because they are being plumbed by different people at different times. Since, typically, one serviceman or one crew will service a plurality of operating wells, the lack of plumbing standardization makes maintenance difficult and it also makes it difficult to train people to service the wells once they are in full production.
Still another difficulty that is encountered is that all of these wells have a finite life. In other words, at some point the production will drop to the point where further production is uneconomical. Under the conventional system, the plumbing is more or less of a permanent nature and in order to move it from one well site to another, it is necessary to completely disassemble it. As a practical matter, the result is that a lot of the material such as tanks, tubing, etc., is rendered useless and this, of course, adds to cost of transferring the plumbing fixtures from one site to another.
Even if the materials are salvagable, a move is still also extremely costly. For example, it has been estimated that currently, with a typical well, an expense of something like $5,000.00 can be involved in a move of this type and, even then, the equipment is never reset the same way at the second well site and, therefore, additional or replacement plumbing materials are required. In other words, it is not possible to physically pick up the plumbing apparatus as a unit and move it to the subsequent site for reuse.